New customers come from the actions of past customers. This can happen in one of three ways: The “sticky engine of growth”—Word of mouth referral is higher than the natural attrition rate (and so growth compounds). The “paid engine of growth”—We can take the revenue we get from one customer and reinvest it into new-customer acquisition. The “viral engine of growth”—New customers can be recruited into the product as a side effect of normal usage, as in products like Facebook or PayPal, as well as fashion or other trendy products.
